Thorium could help alien life emerge – physics world

Thorium could help alien life emerge

Jan 2, 2013

Rocky exoplanets orbiting some Sun-like stars in the Milky Way galaxy could be hotter and more geologically active than Earth and its solar-system companions, according to researchers in the US. The team looked at the abundance of radioactive elements such as thorium, which heat the interior of planets as they decay and thereby play an important role in how planets evolve. The team concluded that planets that are richer in thorium than Earth could be good candidates for the development of life – making them targets for study by astrobiologists and exoplanet hunters.

The research was done by Cayman Unterborn and colleagues at Ohio State University, who used data gathered by the European Southern Observatory’s High Accuracy Radial Velocity Planet Searcher (HARPS) spectrometer in Chile. The team focused on “solar twins”, which are stars that resemble the Sun in terms of their ages, sizes and general make-up. By looking at the abundances of radioactive elements potassium, thorium and uranium within these stars, the team was able to infer the compositions of any rocky exoplanets that may be orbiting the stars. In particular, exoplanets orbiting a star with more thorium than the Sun, for example, would be likely to contain more thorium than the planets in our solar system.